What is Kapro eye treatment?
The Boston Keratoprosthesis (KPro) is that the most generally used artificial cornea or keratoprosthesis.
it's a treatment option for corneal disease not amenable to plain penetrating keratoplasty (PKP) or keratoplasty .
Continued advances in design and superior postoperative care have resulted in improved outcomes and an exponential increase within the use of the device in recent years.
History
The concept of a man-made cornea is over 200 years old. the primary keratoprosthesis was described in 1789 during the French Revolution by Guillaume Pellier de Quengsy.
The first reported human KPro surgery with a quartz implant was performed by Nussbaum in 1855, although some modern KPro experts note that while Nussbaum may have reported the primary human surgery, in fact, Guillaume Pellier de Quengsy’s brother, also an ophthalmologist, may have actually been the primary to perform the surgery during a human.
In recent decades multiple synthetic corneas are pioneered and developed, though only three are principally utilized in practice: the Boston Keratoprosthesis the AlphaCor and therefore the osteo-odonto keratoprosthesis also referred to as the ‘OOKP’.
The Boston Keratoprosthesis has evolved from original concept to a longtime device over the past fifty years under the lifetime leadership of Claes Dohlman, MD, PhD.
The device was approved by the FDA for marketing in 1992. a lively keratoprosthesis research program continues in Boston, MA and other centers worldwide fostering continued innovation with the device.
Design
The Boston Keratoprosthesis may be a collar button design keratoprosthesis. It consists of three components: a front plate with optical stem, a back plate and titanium locking c-ring.
The foremost recent design is threadless; during assembly the front and back plates are snapped along side corneal tissue sandwiched in-between, which is then wont to suture the device to the attention .
Recent advances in design have contributed to improved outcomes. First, the addition of holes within the back plate allows diffusion of nutritive aqueous to support donor graft stroma and keratocytes.
Second, in 2004, a titanium locking c-ring was added to stop intraocular disassembly of the device. Third, in 2007, the planning was changed from a threaded (screw-type) assembly to a threadless design which simplified assembly and produced less damage to the donor endothelium.
the foremost recent advance in design is that the implementation of a titanium back plate which likely improves biocompatibility and retention, and should reduce complications like retroprosthetic membranes (RPM) and stromal corneal melts.
Indication
Although traditional penetrating keratoplasty (PKP) or corneal transplantation is a longtime treatment for a few sorts of corneal blindness, some conditions aren't amenable to PKP.
Indications for the Boston KPro include multiple graft failures, Stevens-Johnson syndrome (SJS), ocular cicatricial pemphigoid (OCP), other autoimmune diseases, ocular burns (acid and alkali) and other conditions with poor prognosis with traditional PKP. Currently, the Boston KPro is taken into account by some to be a primary treatment option in cases of repeat graft failure, and aniridia, and, by a smaller percentage of surgeons, to be a primary option in cases of herpetic keratitis and pediatric corneal opacities.
Pediatric KPro use especially remains a controversial topic that's widely debated among corneal specialists due to the high level of care needed postoperatively and therefore the possibly devastating complications of the procedure.
Surgical procedure
Prosthokeratoplasty is that the term for a procedure during which a damaged cornea is replaced with a man-made cornea.
During implantation of the Boston KPro, the device is assembled with a donor keratoplasty positioned between the front and back plate, that's then sutured into place during a similar fashion to PKP.
The surgery could also be administered by any surgeon conversant in PKP, and without the fear of astigmatism thanks to the rigidity of the assembled device.
the present recommendation is removal of the lens at the time of KPro surgery given the inevitable development of cataract as a results of several factors, including long-term postoperative topical steroid use, surgical trauma and other factors .
the first keratoprosthesis surgery is usually combined with other procedures including iridoplasty, glaucoma filtration devices, IOL and membrane removal and core vitrectomy. Please view accompanying video for an in depth review of device assembly and surgery .
Postoperative management
Closely monitored, long-term follow-up with an ophthalmologist conversant in the KPro may be a necessity with the device.
the substantial risks of glaucoma and endophthalmitis, it's going to be best to manage these patients during a team setting consisting of a corneal specialist, glaucoma specialist, and retinal specialist.
It must be stressed that KPro eyes require life-long follow-up entailing the commitment of the both the patient and ophthalmologist.
The rigorous follow-up should guide patient selection. Furthermore, patient compliance with postoperative medication is of paramount importance.
KPro surgery during a historically non-compliant patient should proceed with extreme caution.
Due to incomplete biointegration of hardware within the eye there's a big risk of infectious endophthalmitis , a devastating complication which frequently leads to a considerable loss of vision.
The incidence of IE has been significantly reduced by life-time daily topical antibiotic prophylaxis. The optimal postoperative antibiotic prophylaxis isn't universally prescribed .
Typical regimes include a topical fourth generation fluoroquinolone (moxifloxacin or gatifloxacin) with or without topical vancomycin.
the rise in incidence of gram-positive IE cases in one study was the idea for the addition of topical vancomycin (preserved with 0.005% benzalkonium chloride which allows storage at temperature for up to 60 days – this lowered cost and improved patient compliance) to the prophylaxis regime in some patients. Most surgeons recommend a topical fluoroquinolone and topical vancomycin within the initial postoperative period of all KPro eyes then continuing dual agent coverage in autoimmune or monocular patients.
In lower risk groups, one agent topical fluoroquinolone or polymyxin B/trimethoprim 2-3 times daily can provide effective long-term antibiotic prophylaxis. Some KPro surgeons recommend antibiotic cycling to stop microbial resistance, although there are not any published studies to support this.
no matter regime employed, the incidence of this devastating complication is reduced with permanent topical antibiotic prophylaxis and patients should be educated on the important of compliance.
Another postoperative management intervention is that the indefinite placement of a bandage contact (BCL).
Placement of a BCL is required to take care of adequate ocular surface hydration and stop stromal melt, dellen formation and necrosis. The BCL has many other added benefits including improving patient comfort and protecting from possible exposed sutures.
The advantage of the BCL is multifactorial and may include other therapeutic, refractive and cosmetic roles. Ocular surface exposure can cause KPro melt and failure and sometimes a tarshorraphy is important additionally to the BCL. The downside to BCL use is that the increased risk of infection related to contact use, especially when used on a chronic, extended wear basis.
Life-long topical steroids like prednisolone acetate is important altogether KPro eyes to stop inflammation and has been successfully utilized since inception of the device. Since steroids can cause IOP elevation, reduce host defenses and inhibit wound healing, KPro patients require close follow-up and monitoring for these and other potential complications.
Complication
The three most ordinarily reported postoperative complications are retroprosthetic membrane (RPM), elevated intraocular pressure/glaucoma and infectious endophthalmitis (IE) which can be discussed here.
Other less frequent complications include sterile vitritis, stromal melt, detachment of the retina and vitreous hemorrhage.
The incidence of RPM in clinical series is reported to be between 25 and 65%. it's believed inflammation is that the most vital factor for RPM formation. Most cases are successfully treated with simple, single session YAG membranotomy.
Typically surgical membranectomy is reserved for cases refractory to YAG laser treatment.
The YAG laser should be used with caution at energy greater than 3.0 mJ because it can crack or pockmark the KPro optic and appropriate technique and laser offsets should be used.
To avoid surgical membranectomy, RPM should be treated before it progresses, thickens and becomes progressively more vascularized rendering it less suitable to YAG membranotomy.
Despite best efforts at RPM monitoring and treatment with YAG laser, some patients will ultimately still progress and need more invasive surgical intervention.
With the many reduction in IE with current antibiotic regimens, glaucoma is now the foremost significant threat to vision in KPro patients.
The reported incidence of glaucoma preoperatively in KPro eyes is 60-76% and postoperative high IOP has been shown in 15-38% of KPro eyes.
Gradual closure of the anterior chamber angle is suspected because the etiology. Monitoring IOP is challenging as traditional tonometry can't be used with the device in situ and measurements believe digital palpation of the sclera.
This complication of KPro surgery is optimally managed in close consultation with an experienced glaucoma specialist and sometimes requires filtration surgery with aqueous shunts and aggressive topical IOP-lowering agents.
Infectious endophthalmitis may be a catastrophic complication often leading to loss of vision. the foremost comprehensive series reports the general incidence of IE as 2.7% per patient year in effect one among the very best endophthalmitis rates of any ophthalmic surgery currently performed. For perspective, this is often 67.5x's above the speed for cataract surgery, and 13.5x's above the speed for glacuoma filtering surgery.
Clinically this complication presents as a sudden onset of ocular pain, scleral injection, and intraocular inflammation manifested by anterior and/or vitreous turbidity (often with hypopyon) and decreased vision. this is often in contrast to sterile vitritis which also presents with a decrease in vision.
On exam, flocculent vitritis is seen but typically without the pain, tenderness or conjunctival injection seen with IE. Final vision after an episode of IE is closely correlated with the causative agent - eyes infected with Streptococci or Staph. Aureus end in poorer vision in comparison to Staph. epidermis or Strep. viridians infections. If IE occurs, immediate evaluation and treatment is required.
Aqueous and/or vitreous samples should be examined and cultured for bacteria and fungi. Intravitreal injection of vancomycin, amikacin and dexamethasone is suggested and pars plana vitrectomy is usually necessary.
Hospitalization should be considered so as to ensure compliance with aggressive topical treatment, post-surgical care and possible IV antibiotics.
OPTOMETRY-SHARP VISION
Optometrist